I masked around the damaged piston and then used a scotchbrite disk on my die grinder to clean up the high spots. There are now no sharp points that could get too hot and cause preignition.
Afterward, I cleaned all of the RTV off of the intake manifold. That stuff sticks surprisingly well. I cleaned most of it off with a razor blade and then used a brass brush to clean off the remaining bits. I’ll use some solvent to get this spotless before reassembling the engine.